[032/119] pps: locking scheme fix up for PPS_GETPARAMS

Greg KH
2009-12-07T00:13:03Z

[-- Attachment #1: pps-locking-scheme-fix-up-for-pps_getparams.patch --]
[-- Type: text/plain, Size: 1191 bytes --]

2.6.31-stable review patch. If anyone has any objections, please let us know.

------------------
From: Rodolfo Giometti <giometti@linux.it>

commit cbf83cc5a29dba480cf1ba1c5e3417a0d4a31410 upstream.

Userland programs may read/write PPS parameters at same time and these
operations may corrupt PPS data.

Signed-off-by: Rodolfo Giometti <giometti@linux.it>
Tested-by: Reg Clemens <clemens@dwf.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
drivers/pps/pps.c | 11 ++++++++---
1 file changed, 8 insertions(+), 3 deletions(-)

--- a/drivers/pps/pps.c
+++ b/drivers/pps/pps.c
@@ -71,9 +71,14 @@ static long pps_cdev_ioctl(struct file *
case PPS_GETPARAMS:
pr_debug("PPS_GETPARAMS: source %d\n", pps->id);

- /* Return current parameters */
- err = copy_to_user(uarg, &pps->params,
- sizeof(struct pps_kparams));
+ spin_lock_irq(&pps->lock);
+
+ /* Get the current parameters */
+ params = pps->params;
+
+ spin_unlock_irq(&pps->lock);
+
+ err = copy_to_user(uarg, &params, sizeof(struct pps_kparams));
if (err)
return -EFAULT;